Insect pathogenic nematodes of the family Steinernematidae are known to be symbiotically associated with bacteria of the genus Xenorhabdus. It has been observed that these bacteria have the ability to kill a wide range of different insects without the aid of their nematode partners.
The present inventors have identified a new class of toxins. A DNA fragment encoding one of these toxins has been isolated from Xenorhabdus nematophilus stain A24 and characterised by sequencing. As will be recogised by persons skilled in the art, DNA fragments encoding members of this new class of toxins may be usefully introduced into viral agents, including entomopox and nuclear polyhedrosis viruses; bacteria (including Gracilicutes, Firmicutes, Tenericutes and Mendosicutes); fungi; protozoa; and plants.